Inhalation represents a very attractive, rapid and patient-friendly route for the delivery of systemically acting drugs, as well as for drugs that are designed to act locally on the lungs themselves. It is particularly desirable and advantageous to develop technologies for delivering drugs to the lungs in a predictable and reproducible manner.
The key features which make inhalation an exciting drug delivery route are: rapid speed of onset; improved patient acceptance and compliance for a non-invasive systemic route; reduction of side effects; product life cycle extension; improved consistency of delivery; access to new forms of therapy, including higher doses, greater efficiency and accuracy of targeting; and direct targeting of the site of action for locally administered drugs, such as those used to treat lung diseases such as asthma, COPD, CF or lung infections.
However, the powder technology behind successful dry powders and DPI products remains a significant technical hurdle to those wishing to succeed with this route of administration and to exploit the significant product opportunities. Any formulation must have suitable flow properties, not only to assist in the manufacture and metering of the powders, but also to provide reliable and predictable resuspension and fluidisation, and to avoid excessive retention of the powder within the dispensing device.